Adding longer (3 inch) screws into your deadbolt plate.
Is this a good idea or effective?
Short Answer: Absolutely.
This is a quick and easy method to increase the force your doorway can withstand before it is breached.
However, the critical Question to be asked is:
Will longer screws be enough to stop a 250 lb man violently kicking-in your door?
PROBABLY NOT. It may delay him.
It is important to note that the door frame is not the only place that “blows out” during a kick-in attack.
The area on the door itself hollowed out to accommodate the deadbolt and was structurally weakened and cannot be strengthened by the longer screws.
By only reinforcing the door frame with longer screws, you have will divert the full force of the kick to this critically weakened point on your door. Now, Most likely a single strong kick will easily blow out this portion of your door.